JP3133633B2 - Conductive composite fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive fiber, and more particularly, to a conductive conjugate fiber which has excellent whiteness and can be suitably used for applications such as carpets and textiles.

[0002]

2. Description of the Related Art Conventionally, as an example of imparting conductivity to fibers, a conductive component in which conductive carbon black is dispersed in a resin and a protective component made of a fiber-forming thermoplastic resin are joined. Conductive composite fibers are known. The conductive carbon black used there is the most conductive material among various non-metallic conductive materials.
It is heavily used. However, a drawback of conductive carbon black is that the conductive fiber to which it is added exhibits a black color, which limits the range of application to carpet and clothing applications. In recent years, in order to solve this disadvantage, particles of a conductive metal compound mainly containing a white metal oxide have been increasingly used in place of conductive carbon black. (Japanese Patent Publication No. 1-2365, etc.)

[0003]

The performance required of a thermoplastic resin (sometimes referred to as a matrix) for dispersing the conductive white metal compound particles (hereinafter sometimes referred to as conductive particles) is as follows. It is possible to disperse the conductive particles at the highest possible concentration without excessively agglomerating them, and it is natural that they have heat resistance enough to withstand melt spinning. It is important. In this regard, it can be generally said that when a crystalline thermoplastic resin is used, mixing a large amount of conductive particles reduces the flexibility of the mixture, lowers the spinnability in melt spinning, and particularly at room temperature. There is a problem that the state of chain formation of the conductive particles is easily broken by breaking due to the stretching below, and as a result, the conductivity is significantly reduced. In this sense, general-purpose polyethylene, polypropylene, polyamide, and polyester resins have high crystallinity, have good heat resistance, and are approved for the general tendency of being advantageous in melt spinning. Is not always appropriate.

[0004] In connection with the above-mentioned problem, a proposal for using a thermoplastic elastomer as a matrix has been proposed in Japanese Patent Laid-Open No. Hei.
No. 153305. Examples of the thermoplastic elastomers described therein include olefin addition polymerization types such as styrene / conjugated diene block copolymers, polyurethane, polyamide and polyester polycondensation types, and synthetic rubber types. Things are listed. However, these thermoplastic elastomers are listed only in general names, and not all types belonging to them are arbitrarily selectable for the above purpose. For example, the above-mentioned styrene / conjugated diene-based block copolymer has a high apparent viscosity at the time of melting, and loses fluidity to such an extent that spinning and drawing is almost impossible when blending conductive particles in a high concentration. To avoid this inconvenience, if a type having a high fluidity is used, the molecular weight must be reduced, and a decrease in heat resistance cannot be avoided.

[0005] In addition, the present applicant previously relates to the above problem, and in order to suppress the deterioration of conductive performance due to stretching, as a matrix mainly for dispersing conductive metal compound particles, a matrix having 4 to 10 carbon atoms is used. The use of an addition polymer of α-olefins has been proposed in Japanese Patent Application No. 2-191067.
By using such a matrix, it is possible to obtain a conductive conjugate fiber having a small decrease in conductivity due to stretching. However, such α-olefin-based polymers do not always have sufficient heat resistance mainly due to the presence of their side chains, and particularly when the nonconductive component is a high melting point resin such as 66N or polyester, a high spinning temperature is required. The high temperature causes thermal decomposition of the α-olefin-based polymer, lowers the discharge stability of the conductive component in the composite spinning, and causes insufficient spinning operability. Also,
Since the α-olefin-based polymer is an aliphatic hydrocarbon compound, it is basically easily dissolved in a non-polar organic solvent, and there is a concern that the dry cleaning resistance is poor in practical use.

[0006]

SUMMARY OF THE INVENTION The present inventor has found that even when a resin such as 66N or polyester is used as a non-conductive component, a high spinning temperature is required, the heat resistance is good and the fluidity is high. As a result of various investigations on a matrix that can suppress a decrease in the conductivity, can provide a high conductivity to the fiber and can give a high conductivity to the fiber, and can suppress a decrease in the conductive performance by stretching, a specific composition of The present inventors have found that an ethylene copolymer resin satisfies these conditions, and have completed the present invention. That is, the present invention relates to a conductive layer in which a conductive layer made of a conductive master-resin composition obtained by kneading conductive white metal compound particles into a thermoplastic resin and a non-conductive layer made of a fiber-forming thermoplastic polymer are joined. In the conductive conjugate fiber, the thermoplastic resin as a component of the conductive layer is a copolymer of ethylene and an unsaturated carboxylic acid or its alkyl ester.

As examples of unsaturated carboxylic acids or alkyl esters thereof which are monomer components copolymerized with ethylene, unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid and fumaric acid. , As unsaturated carboxylic acid alkyl esters, methyl acrylate, ethyl acrylate, butyl acrylate,
Acrylic acid esters such as 2-hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate,
Examples include methacrylates such as 2-ethylhexyl methacrylate and unsaturated dibasic acid diesters such as diethyl maleate and diethyl fumarate. Among the above various copolymers, a copolymer of ethylene and acrylic acid (usually EAA), a copolymer of ethylene and ethyl acrylate (EEA), and a copolymer of ethylene and methyl acrylate (EMA) Is preferred in terms of heat resistance and availability.

The copolymerization ratio of the monomer component to be copolymerized with ethylene is 3 to 18% by weight, preferably 6 to 15% by weight based on the whole. When the copolymerization ratio is less than 3% by weight, the properties of the copolymer are naturally similar to those of polyethylene, and the conductive particles cannot be dispersed at a high concentration. On the other hand, when the content exceeds 18% by weight, the melting point or softening point of the copolymer is extremely lowered, which adversely affects the spinnability, the processing steps after fiberization and the practicality in textile products.

Further, the melt index of the ethylene copolymer needs to be 0.3 to 25 (measured at 190 ° C.). When it is less than 0.3, the fluidity is reduced when the conductive particles are kneaded at a high concentration, and the spinnability during spinning is lost. On the other hand, when it exceeds 25, the melt heat resistance decreases, so that satisfactory spinning cannot be performed. Even when conductive particles of the same concentration are added, the lower the melt index of the original matrix, the lower the flowability after addition and the higher the apparent viscosity. The selection of the optimal melt index for satisfactory composite spinning is based on this characteristic, and depending on the mixing ratio of the conductive particles and the type of the fiber-forming thermoplastic polymer constituting the non-conductive layer, the composite spinning is selected. The temperature may be appropriately determined within the above range in consideration of that the apparent viscosity of the conductive layer and the non-conductive layer does not greatly differ at the temperature.

[0010] Crystalline resins such as polyethylene which have been conventionally used become extremely brittle with respect to elongation when they are mixed with conductive particles at a high concentration, and are easily cut. Since the coalescing is a flexible resin having elastic properties, the conductive layer containing the conductive particles has excellent spinnability, can follow the melt tension during spinning and the stress during stretching, and hardly causes thread breakage. It becomes. Further, these ethylene copolymers have good dispersibility of conductive particles as compared with crystalline resins, and enable high-content blending of the particles.

As the conductive white metal compound particles used in the present invention, all kinds of conductive white metal compound particles can be used as long as they have a specific resistance of 10 ⁴ Ω · cm or less.
For example, a metal oxide having conductivity, such as stannic oxide, zinc oxide, indium oxide, zirconium oxide, and tungsten oxide, added with a small amount of a suitable second component (dopant) can enhance conductivity. Because it can be used, it can be suitably used. Such a second component includes an oxidized second component.
Antimony oxide is used for tin, and aluminum oxide, indium oxide, germanium oxide, tin oxide, or the like is used for zinc oxide. In addition, it is most preferable that the surface of the white metal oxide particles is covered with a conductive metal oxide. For example, a film having tin oxide as a main component and antimony oxide as a dopant is formed on the surface of titanium oxide particles. The conductive particles to which is added are most preferable in terms of whiteness and that uniform particles having a small particle diameter can be obtained.

As described above, the conductivity of the conductive white metal compound particles may have a specific resistance of 10 ⁴ Ω · cm or less.
More preferably, it is 10 ² Ω · cm or less. Most preferably, it is 10 ¹ Ω · cm or less. In addition, the particle size of the conductive white metal compound particles is usually required to be 1 μm or less in order to prevent filter clogging and yarn breakage during spinning. In particular, it is more preferably 0.5 μm or less, and most preferably 0.3 μm or less.

In the present invention, conductive particles are kneaded with an ethylene copolymer to prepare a high-concentration conductive master-resin composition. The kneading concentration depends on the type of conductive particles, the type of ethylene copolymer, Although it varies depending on the conductivity level, about 65 to 90% by weight is often necessary in order to suppress a decrease in conductivity due to stretching. It is known in the art of resin compounding to treat inorganic particles in a matrix with a surface treating agent such as a silane-based or titanate-based coupling agent in order to uniformly disperse the inorganic particles at a high concentration. It is also possible to employ such a surface treatment.

The specific resistance (volume resistivity) of the conductive master-resin composition needs to be less than 10 ⁵ Ω · cm, preferably less than 10 ² Ω · cm. Is good. As the fiber-forming thermoplastic polymer used as a non-conductive component in the composite fiber of the present invention,
There is no other limitation as long as it is a polymer material that can be melt-spun, and examples thereof include polyethylene terephthalate, polybutylene terephthalate, 6 nylon, 66 nylon, and polypropylene. Known additives such as a matting agent, a pigment, a colorant, a stabilizer, and an antistatic agent may be added to these polymers as needed.

In the conductive conjugate fiber of the present invention, known bonding forms can be applied to the nonconductive layer and the conductive layer. For example, a core-sheath type as illustrated in FIG. 1 and FIG.
Multi-core type) and a bimetal type as shown in FIG. 3 are preferable, but a type in which a part of the conductive layer is slightly exposed on the fiber surface as illustrated in FIG. 4 is also preferable. Further, the contour of the fiber may be circular or non-circular. The composite ratio is also not particularly limited as long as it does not affect the spinnability or the high elongation of the fiber, but in many cases,
The conductive layer occupies 3 to 60% in cross-sectional area ratio. The spinning method can be carried out according to an ordinary method for producing a composite fiber.

[0016]

【Example】

[Example 1] Conductive particles having an average particle diameter of 0.2 µm obtained by mixing and firing 1.5% by weight of antimony oxide with titanium oxide particles having a 15% by weight coating of stannic oxide on the surface (Mitsubishi Materials Corporation) (Available as W-1 manufactured by Co., Ltd.). The conductive particles are mixed with an ethylene / ethyl acrylate copolymer resin (commonly referred to as E) using a biaxial kneader.
(EA, ethyl acrylate ratio: 7% by weight, melt index value: 15, melting point: 110 ° C) was melt-kneaded at 235 ° C to a concentration of 75% by weight to obtain pellets of the conductive resin composition. The specific resistance of this composition is 7 × 10 ² Ω ·
cm. This is used as a conductive component in the composite spinning.
On the other hand, a bright nylon 66 pellet having a relative viscosity of 2.63 in a 1% solution in 96% sulfuric acid measured at 25 ° C. at 25 ° C. was used as a non-conductive component, and composite spinning was carried out together with the above-mentioned conductive component according to a standard method. Fig. 1 shows the main conditions for spinning.
Nozzle diameter 0.25m to give fiber cross-sectional shape as shown in
m, the composite ratio is such that the volume ratio of conductive component to non-conductive component is 1 to 10, and the spinning temperature is 29.
0 ° C. The filament is spun out in this manner and 800
It was wound at m / min to obtain an undrawn yarn. Even after 6 hours from the start of spinning, no increase in pack pressure was observed. The obtained undrawn yarn was drawn at room temperature at each magnification as shown in Table 1,
A drawn yarn of 0 denier and 6 filaments was obtained. Table 1 shows the measured values of the specific resistance of the yarn. When the draw ratio is 3.8 times, the fluff is conspicuous and drawing cannot be performed.

[Table 1]

[Examples 2 to 8, Comparative Examples 1 to 3] As shown in Table 2, an ethylene copolymer having a composition in which monomer components to be copolymerized with ethylene were variously changed was used as a matrix, and conductive particles were used in Example 1. W-1 (particle size 0.0
5 μ) was mixed with 80% by weight to prepare a conductive resin composition. The kneading was performed in the same manner as in Example 1, and the kneading temperature was 238 ° C. In order to evaluate the fluidity of the composition that could be kneaded, the composition was melted at 250 ° C. using a melt indexer, discharged from a 0.5 mm diameter orifice under a load of 10 kg, and 6 to 9 minutes after the start of melting. The outflow for 3 minutes up to that point was measured, multiplied by 10/3, and a numerical value converted to the outflow per 10 minutes was obtained. Table 2 shows the above results. The larger the value, the better the fluidity. Next, the composition obtained above is used as the conductive component in the composite fiber, while the non-conductive component is the intrinsic viscosity [η] at 20 ° C. in a 6/4 (weight ratio) mixed solvent of phenol / tetrachloroethane. Using a semi-dal polymer of polyethylene terephthalate having a ratio of 0.67 dl / g and composite spinning in a composite form shown in FIG. 2 (composite ratio is 1:14 by volume ratio of conductive component to nonconductive component) according to a standard method.
The main spinning conditions include a spinning temperature of 285 ° C. and a winding speed of 1.
000 m / min. The rolled unstretched yarn is set to 3.18 at a roller / heater temperature of 80 ° C / 150 ° C.
It was drawn twice to obtain a drawn yarn of 20 denier / 3 filaments. The specific resistance of the obtained drawn yarn is also shown in Table 2.

[0018]

[Table 2]

[Comparative Example 4] The same method and conditions as in Example 1 were used except that a linear low-density polyethylene (melt index 3) was used as the conductive matrix and the mixing ratio of W-1 was 70%. Composite spinning was performed to obtain a drawn yarn. An increase in the pack pressure was observed at about 3.5 hours after the start of spinning, and a long-time stable undrawn yarn could not be wound up. In addition, many yarn breaks occurred during stretching, and industrial-level production was impossible.

Comparative Example 5 Califlex TR11, a kind of styrene / conjugated diene-based thermoplastic elastomer
01 [manufactured by Shell Petrochemical Co., Ltd., has a melt index of 0.02 measured at 230 ° C. and cannot be measured at 190 ° C. without discharging] as a matrix and W-1 having an average particle size of 0.2 μm as conductive particles. And the mixing ratio of W-1 is 70
% And kneaded in a matrix to prepare a conductive master chip. The kneading method is the same as in Example 1,
The kneading temperature was searched in the range of 255 to 280 ° C. for the condition for obtaining the optimum discharge state. At 280 ° C., the fluidity of the kneaded material gradually decreased, and gelation appeared to occur. At lower temperatures, the screen pressure gradually increased, and the biteability of the matrix resin into the hopper became poor.

[0021]

The conductive conjugate fiber of the present invention using an ethylene copolymer has high conductivity because the conductive layer contains a high concentration of conductive particles, and has a low conductivity even when stretched at room temperature. Is slight. In addition, the fiber is excellent in flexibility,
Even if the product is mixed into clothing and carpets, the product maintains its flexibility and has good affinity between the matrix and conductive particles, so it is conductive against repeated stretching and impact during use. An antistatic fiber product with good durability and with less deformation and destruction of the layer can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a cross-sectional shape of a conductive conjugate fiber of the present invention.

FIG. 2 is a diagram showing another example of the cross-sectional shape of the conductive conjugate fiber of the present invention.

FIG. 3 is a diagram showing still another example of the cross-sectional shape of the conductive conjugate fiber of the present invention.

FIG. 4 is a view showing still another example of the cross-sectional shape of the conductive conjugate fiber of the present invention.

[Explanation of symbols]

 A Conductive layer made of conductive master resin composition B Non-conductive layer made of fiber-forming thermoplastic polymer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-289108 (JP, A) JP-A-4-50316 (JP, A) JP-A-3-161512 (JP, A) JP-A-61- 201014 (JP, A) JP-A-60-110920 (JP, A) JP-A-59-21722 (JP, A) JP-A-57-5919 (JP, A) JP-B 1-222365 (JP, B2) (58) Field surveyed (Int.Cl. ⁷ , DB name) D01F 8/10 D01F 8/04 D01F 1/09

Claims (2)

(57) [Claims] 1. A conductive material in which a conductive layer made of a conductive master-resin composition obtained by kneading conductive white metal compound particles in a thermoplastic resin and a non-conductive layer made of a fiber-forming thermoplastic polymer are joined. A conductive conjugate fiber, wherein the thermoplastic resin for kneading the conductive white metal compound particles is a copolymer of ethylene and an unsaturated carboxylic acid or an alkyl ester thereof. 2. The copolymerization ratio of the unsaturated carboxylic acid or its alkyl ester in the copolymer is 3 to 18% by weight, and the melt index of the copolymer measured at 190 ° C. is 0.3%. The electrically conductive conjugate fiber according to claim 1, wherein